Well, that's too bad. Most of the best DW novels are pre-Ninth Doctor, and many of the current show's writers (Russell T Davies, Paul Cornell, Mark Gatiss, Gareth Roberts) started there.

Tell me about the new ones that follow Doctors 9 to 11. Are they good? Are they aimed more at children or adults?

Some of them are good, sure. And they're aimed somewhere between children and adults. Writers like Lance Parkin will say that they wrote their New Series Adventures (the turtleback books that make up most of the current novels) pretty much the same way they wrote their New Adventures or Eighth Doctor Adventures novels, but the fannish consensus seems to be that the NSAs do skew simpler/younger. I think so, anyway.

There's a small number of novels published as standard size hardcovers that are more adult-oriented, but there's maybe half a dozen or so and they're not all 9 and up. They tend to be written by bigger SF names from outside the tie-in world -- Michael Moorcock, Stephen Baxter, Alastair Reynolds, etc.

Is there any kind of continuity?

Not in the NSAs, no. For continuity you'd want the NAs and EDAs.

Are the 2-in-1 books worth reading?

They skew a bit younger than the NSAs, I believe. I haven't read any of them yet.

What's The Darksmith Legacy?

A miniseries of kids' books with some optional "interactive" elements on a dedicated website. Haven't read them yet either, though I have them, but they appear to skew at least as young as the 2-in-1 books.

Anything else I should know?

There are a few ebook-only titles. There have been three that tie into Eleventh Doctor episodes, though not by much (The Angel's Kiss: A Melody Malone Mystery, Devil in the Smoke, Summer Falls) and a monthly series of anniversary short stories working through all the Doctors, one at a time.

But 90% of the Doctor Who books that get me excited have their roots in the first Eight Doctors. The New Adventures, the Missing Adventures, the Eighth Doctor Adventures, the Past Doctor Adventures, the Telos novellas, Faction Paradox, Bernice Summerfield, Iris Wildthyme, Time Hunter... those are where a lot of the best stuff is.